"This is good news for Rugby and shows the healthy state the sport is in as regards attracting top-class commercial partners," said IRB Chief Executive Brett Gosper.
"Specsavers has a proven track record within the sports sector and we are looking forward to working closely with them."
Specsavers chairman and former Llanelli second row Doug Perkins added: "Good eyesight is clearly very important in competitive sport. While there continues to be exciting technological innovations to aid referees, we will always rely on their personal judgement too. At Specsavers we're glad to do our bit where we can to help ensure that they get the best possible support to do their job."
Specsavers will be supporting the tour, which runs from June 1 to July 6, with sponsorship of the referees running in conjunction with a typically innovative advertising campaign across television, internet and social media.
In addition to the Lions match officials, Specsavers is building on its existing portfolio of sporting sponsorships that includes the Scottish Football Association match officials, RaboDirect PRO12 and women's GAA in Ireland.